1. Field of the Invention
The present invention relates to a processing method for dividing an optical device wafer into individual devices.
2. Description of the Related Art
In an optical device chip manufacturing process, light emitting devices such as light emitting diodes and laser diodes are formed respectively in regions partitioned by a plurality of crossing streets formed on a surface of a crystal growth substrate such as a sapphire substrate or a silicon carbide substrate, to produce an optical device wafer. Thereafter, electrodes are formed, and the optical device wafer is divided along the streets, to manufacture individual optical device chips.
In recent years, from the viewpoint of enhanced productivity, pulsed laser processing apparatuses have widely been used for dividing optical device wafers. In a pulsed laser processing apparatus, a pulsed laser beam is applied to the surface of an optical device wafer along streets to form laser processed grooves, and the optical device wafer is divided, with the laser processed grooves as start points of division, into individual chips (see, for example, Japanese Patent Laid-open No. Hei 10-305420). When laser processing is applied to an optical device wafer as above, strain is generated in side surfaces of the laser processed grooves. In view of this, there has been proposed, for example in Japanese Patent Laid-open No. 2006-024914, a method for removing such strain by subjecting the optical device wafer to dry etching or wet etching prior to division of the optical device wafer, whereby the optical device chips manufactured are enhanced in brightness.